Murine studies investigating cytokine and protease levels after e-cigarette exposure. Summary of murine studies investigating inflammatory cytokine and protease levels in BAL fluid following e-cigarette exposures of varying lengths, in comparison to air exposed control mice. Representative examples of acute, subacute and chronic murine cigarette smoke exposure models are included for comparison.

Author [ref.]YearE-cigarette specificationECL detailsExposure regimeCells in BALCytokines in BAL
Sussan [44]2015NJOY vape pen18 mg·mL−11.5 h twice per day, 14 daysNo increase in neutrophil, eosinophil or lymphocyte count Increased macrophage countMCP-1IL-6
Lerner [42]2015Blu vape pen16 mg·mL−15 h·day−1, 3 daysNo increase in macrophage countIL-6, IL-1α, IL-13, MCP-1IL-10,# IL-1β,# KC,# IL-17, GMCSF, CXCL10, MIP2
Wang [45]2020Joytech box-mod25 mg·mL−1 (0 mg·mL−1 control arm)2 h·day−1, 30 daysIncrease in macrophage, CD4 T-cell and CD8 T-cell count No increase in neutrophil countMCP-1, IL-1α, TNFα, GMCSF, MIP-1B, IL-2, IL-5, IL-9, IFNγ, RANTES
Hwang [43]2016Vape pen24 mg·mL−11 h·day−1, 28 daysNo increase in macrophage, neutrophil, eosinophil or lymphocyte countsKC, IL1rαGMCSF, IL-3
Madison [46]2019Vape pen/box-mod33 mg·mL−16 min·day−1, 4 monthsNo increase in macrophage, neutrophil or lymphocyte count No increase in dendritic cell or Th17 cell countNot investigatedNot investigatedNot investigated
Vlahos [47]2006Commercially available filter-tipped cigarettes3, 6 or 9 cigarettes per day, 4 daysDose-dependent neutrophil increase Increased macrophages with 9 cigarettes per day No increase in lymphocyte countTNFα,+ MIP2,+ IL-6,+ GMCSF+IL-10+
Beckett [50]20133R4F reference cigarettesTwice per day, 5 times per week, 1–12 weeksIncreased macrophage and neutrophil count at 4 days and 8 weeks Increased lymphocyte count at 8 weeksTNFα,+ IL-1β,+ CXCL1+
Phillips [51]20153R4F reference cigarettes1 h 4 times per day, 5 days per week, 7 monthsIncreased macrophage, neutrophil, lymphocyte and dendritic cell countGMCSF, IFNγ, IL-1α, IL-6, IP10, MCP1 TNFα, MIP1, MIP2IL-10, IL-1β
Motz [52]20103R4F reference cigarettes4 h·day−1, 5 days per week, 24 weeksIncreased macrophage/monocyte, neutrophil and lymphocyte countNot presentedNot presented

ECL: e-cigarette liquid; BAL: bronchoalveolar lavage; MCP: monocyte chemoattractant protein; IL: interleukin; KC: keratinocyte-derived chemokine; GMCSF: granulocyte-macrophage colony-stimulating factor; CXCL: chemokine (C-X-C motif) ligand; MIP: macrophage inflammatory protein; TNF: tumour necrosis factor; IFN: interferon; RANTES: regulated on activation, normal T-cell expressed and secreted. #: Trends suggest increased levels bordering on significance; : changes dependent on nicotine in ECL; +: gene expression levels in whole lung tissue.